{
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\begin{tabular}{l*{2}{c}}
\hline\hline
                    &\multicolumn{1}{c}{\specialcell{\;\;\;\; Arsenic \\ contamination \\ \;\;\;\; (WHO \\ \;\; threshold)}}&\multicolumn{1}{c}{\specialcell{\;\;\;\;\;\; Fecal \\ contamination}}\\\cmidrule(lr){2-2}\cmidrule(lr){3-3}
                    &\multicolumn{1}{c}{(1)}   &\multicolumn{1}{c}{(2)}   \\
\hline
As safe source (baseline) x treated&      -0.013   &      -0.041   \\
                    &     (0.026)   &     (0.030)   \\
Low As Source (baseline) x treated&      -0.025   &       0.005   \\
                    &     (0.036)   &     (0.034)   \\
Moderate As Source (baseline) x treated&      -0.035   &       0.007   \\
                    &     (0.041)   &     (0.059)   \\
High As Source (baseline) x treated&      -0.053   &      -0.055   \\
                    &     (0.034)   &     (0.043)   \\
\hline
R$^2$               &        0.28   &        0.05   \\
N                   &        6051   &        6051   \\
\hline\hline
\end{tabular}
}
